Workload control in dual-resource constrained high-variety shops: an assessment by simulation

Abstract

Workload Control (WLC) seeks to align capacity with demand, where capacity is typically assumed to be restricted by a single constraintmachine capacity. In practice however, shops are often restricted by dual resource constraints: labor and machines. This study therefore uses simulation to investigate the performance of WLC in Dual Resource Constrained (DRC) highvariety shops with fully interchangeable labor. By considering several environmental factors and different labor assignment and dispatching rules, it is demonstrated that the order release function of WLC maintains its positive impact on performance in a DRC shop under different staffing levels. The positive effect of considering labor availability at release, as proposed in previous research, could not however be confirmed. Thus, the original release method can be applied if labor is fully interchangeable. In terms of labor assignment, we show that a distinct assignment pattern that differs between upstream and downstream stations improves performance if the routing is directed. Meanwhile, dispatching plays a less important role but creates important interaction effects with the assignment rule. Finally, the results suggest that increasing the service rate is a better response to the reduction in capacity that results from labor absenteeism than lowering the input frequency of work.

Worker assignment in dual resource constrained assembly job shops with worker heterogeneity: an assessment by simulation

“…There are mainly two types of When Rules applied in the literature: a 'centralized' rule that transfers a worker each time a job is completed and a 'decentralized' rule that transfers a worker after completing all jobs at the current station. The centralized rule tends to outperform the decentralized When Rule but at the expense of an increase in the number of worker transfers (Thürer et al, 2019). Meanwhile, it has been shown that incorporating future workload information into the When Rule does not improve performance enough to impact a manager's decisions (Fredendall et al 1996).…”

“…Only if a worker is assigned to a station is capacity realized and orders can be processed. We use only one staffing level since the impact of different staffing levels has recently been assessed in Thürer et al (2019). We focus on the lowest staffing level from previous studies, i.e.…”

“…Based on results in previous research (e.g. Thürer et al, 2019), only the centralized When Rule is considered, i.e. a worker is eligible for transfer after each work order has been completed at a station.…”

“…Meanwhile, being "dual resource constrained" (DRC) means that the shop is restricted by not one but two resources, most typically by machines and labor (e.g. Felan et al, 1993;Malhotra et al, 1993;Fredendall et al, 1996;Bokhorst et al, 2004a;Bokhorst & Gaalman, 2009;Thürer et al, 2019). Finally, "heterogeneous labor" refers to shops where workers are not perfectly interchangeable, i.e.…”

Workload Control Order Release With Controllable Processing Time Policies: An Assessment by Simulation

“…Based on the release method, the research evaluates the due date assignation considering forecasting system to maximize the on-time deliveries [16,17].…”